|To listen to a serial COM port needs a program since serial communication is an interrupt driven process and that is beyond the features of batch scripting.|
You can try the Open Source package PUTTY (Google for it), a free application driven by command line that can be scriptable too. I never used it but people say it is very effective.
As an alternative I can give you a legacy 16 bit application that still works fine under Vista 32 bit, but that must be customized as I coded it years ago to grab data from lab devices. It may work or not interfacing an emulated COM4 port.
If you are interested contact me via a private message with your e-mail address and specify exactly the format of data stream. Be aware the solution is not immediate as I have to customize and am very busy too.